Four-stroke engine camshaft with stepped cams - starts engine as two stroke system and has three steps for different cam characteristics

摘要

The four stroke reciprocating piston engine has camshaft operated valves and the camshaft has cams each with three steps for a valve. The camshaft is moved axially for bringing a particular cam step in contact with a valve push rod. This system ensures good engine starting, warming up and running characteristics. The internal combustion engine has exhaust gas flow brakes with a throttling flap (14) situated in exhaust gas pipe (13). The camshaft (3) has normal operating cams for the engine and it also ensures a delayed opening period and early closing of the inlet valve for engine starting. In addition the cams operate the gas inlet and outlet valves as in a two stroke engine for starting. Subsequently on reaching the starting speed, the camshaft is moved into position with delayed opening and early closing of inlet valves if outlet temperatures and engine are cold. Finally the camshaft is shifted into regular operating position.